Economic theory predicts that when the costs of quitting one’s job are relatively low, mobility is more likely. This observation underlines the analysis of the rise in quit rates during periods of prosperity, and the effects of mobility costs can be seen when looking at residential location and job turnover. Industries with high concentrations of employment in urban areas, where a worker’s change of employer does not necessarily require investing in a change of residence, appear to have higher rates of job turnover than industries concentrated in nonmetropolitan areas do.

Beyond the costs that can be associated with such measurable characteristics as age and residential location are those that are psychic in nature. These latter costs, though unobservable to the researcher, are very likely to differ widely across individuals. Some people adapt more quickly to new surroundings than others do, for example. Recent studies have found considerable heterogeneity among workers in their propensity to change jobs, with one study reporting that almost half of all permanent separations that took place over a three-year period involved a small number (13 percent) of workers who had three or more separations during the period (in contrast, 31 percent of workers had no separations at all during the period).

It is also possible that the costs of job changing by employees vary internationally. Data suggest that workers in the United States may well be more likely to change employers than workers elsewhere may be. Indeed, data confirm that, on average, American workers have been with their current employers fewer years than workers in most other developed countries, particularly workers in Europe and Japan, have been with theirs. It is not known why Americans are more mobile than most others are, but one possibility relates to the lower levels of company training received by American workers. Another possibility, however, is that the costs of mobility are lower in the United States (despite the fact that Japan and Europe are more densely populated and hence more urban). What would create these lower costs?

One hypothesis that has received at least some investigation is that housing policies in Europe and Japan increase the costs of residential, and therefore job, mobility. Germany, the United Kingdom, and Japan, for example, have controls on the rent increases that proprietors can charge to existing renters while tending to allow proprietors the freedom to negotiates any mutually agreeable rent on their initial lease with the renter. Thus, it is argued that renters who move typically face very large rent increases in these countries. Similarly, subsidized housing is much more common in these countries than in the United States, but since it is limited relative to the demand for it, those British, German, or Japanese workers fortunate enough to live in subsidized units are reluctant (it is argued) to give them up. The empirical evidence on the implications of housing policy for job mobility, however, is both limited and mixed.

It could also be hypothesized that the United States, Australia, and Canada, all of which exhibit shorter job tenures than do most European countries or Japan, are large, sparsely populated countries that historically have attracted people willing to emigrate from abroad or resettle internally over long distances. In a country of “movers,” moving may not be seen by either worker or employer as an unusual or especially traumatic event.

While questions remain about the causes of different job mobility rates across countries, the social desirability of job mobility can also be debated. On one hand, mobility can be seen as socially useful because it promotes both individual well-being and the quality of job matches.Moreover, the greater the number of workers and employers “in the market” at any given time, the more flexibility an economy has in making job matches that best adapt to a changing environment. Indeed, when focusing on this aspect of job mobility, economists have long worried whether economies have enough mobility. On the other hand, lower mobility costs (and therefore greater mobility) among workers may well serve to reduce the incentives of their employers to provide job training. Whether the presence of job changing costs is a social boon or bane, these costs and the mobility associated with them are factors with which all employers must contend.

经济理论预测，当辞职的成本相对较低时，人员的流动性就更有可能发生。这一观察结果突显出，在繁荣时期辞职率上升的分析，并且在观察居住地点和工作人员流动时，可以看到流动成本的影响。在城市就业集中度较高的行业，即工人变更雇主并不一定需要对居住地变更的进行投资，而在非大都市区集中的行业中，其工作人员流动率似乎更高。 除了能与年代和居住地点等可测量的特征相关联的成本之外，还有那些本质上是精神的东西。这些之后的成本虽然对研究人员来说是不可观察的，但很可能在个体间存在很大的差异。例如，有些人比其他人更快适应新的环境。最近的研究发现工人之间有较大的差异性，他们倾向于换工作，有一项研究报告说，大约在三年期间所有永久性离职的一半情况包括了一些（13％）工人在此期间离职3次或更多次（相比之下,31％的工人在此期间根本没有离职）。 此外，员工跳槽的成本也可能在国际上有所不同。数据表明，美国的工人可能比其他地方的工人更有可能更换雇主。事实上，数据证实，美国工人平均而言与其他大多数其他发达国家的工人数量要少的多，特别是对欧洲和日本的工人而言。目前尚不清楚为什么美国人比大多数人更具流动性，但有一种可能性是美国工人接受较低级别的公司培训有关。然而，另一种可能性是，美国的流动成本较低（尽管日本和欧洲人口密度更高，因此也更城市化）。什么会降低成本呢？ 人们提出的一种假设已经进行了一些调查，那就是，欧洲和日本的住房政策增加了住宅的成本，因此例如德国，英国和日本的就业，流动性控制了房东租金增加，同时倾向于允许业主自由地与承租人谈判关于最初租赁双方都同意的租金。因此，有人认为，这些国家的租户通常会面临很大的租金上涨情况。同样，这些国家的补贴住房比美国更为普遍，但由于它的供给相对需求有限，英国，德国或日本的工人很幸运的生活在补贴单位里，所以他们不愿意（有人说）放弃补贴。然而，关于住房政策对工作流动性影响的实证证据既有限又复杂。 同样也可以假设，美国、澳大利亚和加拿大都比大多数欧洲国家或日本工作的时间短，这些国家都是人口众多、人口稀少的国家，历来都吸引了愿意移民海外的人，或者在遥远的地方重新定居的人。在一个“搬家者”的国度里，无论是工人还是雇主，都不可能将其视为一件不寻常或特别痛苦的事情。 尽管不同国家不同岗位流动率的原因仍存在疑问，但就业流动性的社会吸引力也存在争议。一方面，流动性可以被看作是社会有用的，因为它可以促进个人的幸福和提高了工作的质量。此外，在任何特定时间“在市场上”的工人和雇主的数量越多，经济就越能灵活地适应变化的环境。事实上，当关注就业流动性的这一方面时，经济学家一直担心经济是否有足够的流动性。另一方面，工人之间的流动性成本较低（因此流动性较大）可能会降低雇主提供职业培训的积极性。无论工作成本的变化是社会福利还是灾祸，这些成本和与之相关的流动性都是所有雇主都必须应对的因素。